Electrophotographic copying apparatus

ABSTRACT

An electrophotographic copying apparatus in which an original and a copy sheet are advanced during reproduction in a downwards direction along mutually spaced, substantially vertical conveying paths, start positions for the advancement of the original and the copy sheet being defined by stop members inserted into the respective conveying paths, which stop members are retracted from their inserted positions in a timed sequence with the start of a main driving system, the advancement of a copy sheet from a sheet supply to the copy sheet conveying path and the operation of a corona charging unit and an exposure lamp, by programming means including a single disc-shaped timing member which is mounted for rotation in the apparatus and is coupled with the main driving system, said timing member actuating all of the control functions in a correctly timed sequence during a single revolution.

Zeuthen [451 Nov. 19, 1974 ELECTROPHOTOGRAPHIC COPYING APPARATUS KarlGustav Zeuthen, Gentofte, Denmark [75] Inventor:

[73] Assignee: Rexomi A/S, Copenhagen, Denmark [22] Filed: Oct. 12, 1973[21] Appl. No.: 405,907

[30] Foreign Application Priority Data Oct. 17, 1972 Denmark 5123/72[52] U.S. Cl. 355/14, 355/3 R [51] Int. Cl 603g 15/00 [58] Field ofSearch 355/3 R, 14

[56] References Cited UNITED STATES PATENTS 3,490,843 l/l970 Charlap eta]. 355/14 3,711,198 l/l973 Nordine 355/14 X Primary ExaminerRobert P.Greiner Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [57]ABSTRACT An electrophotographic copying apparatus in which an originaland a copy sheet are advanced during reproduction in a downwardsdirection along mutually spaced, substantially vertical conveying paths,start positions for the advancement of the original and the copy sheetbeing defined by stop members inserted into the respective conveyingpaths, which stop members are retracted from their inserted positions ina timed sequence with the start of a main driving system, theadvancement of a copy sheet from a sheet supply to the copy sheetconveying path and the operation of a corona charging unit and anexposure lamp, by programming means including a single disc-shapedtiming member which is mounted for rotation in the apparatus and iscoupled with the main driving system, said timing member actuating allof the control functions in a correctly timed sequence during a singlerevolution.

7 Claims, 13 Drawing Figures PATENTEL HUN 9 I974 SHEET 10F 7 FIG. 1

PATENTELHUVIQIW 7 3,848,991

SHEET 30F 7 FIG. 3

PATENTEL WV 1 9 I974 SHEET 4 OF 7 FIG.

PATENTEL HUV 1 9 I974 SHEET 6 OF 7 ELECTROPIIOTOGRAPI-IIC COPYINGAPPARATUS The present invention relates to an electrophoto- I BACKGROUNDOF THE INVENTION A copying apparatus of this kind is described inapplicants copending U.S. patent application Ser. No. 358,325 filed onMay 8, 1973 which is a continuationin-part of applicants prior U.S.application Ser. No. 112,565 now abandoned. This copying apparatus hasthe advantage of being of a simple structure, so that it can bemanufactured and sold at a low price and presenting an easy operationfor the user. Above all, the apparatus is of a limited size so that aminimum of space is required for its installation due to the fact, interalia, that accessibility is only required to the front of the apparatuswhich may therefore be hanged directly on a wall.

In the art of electrophotographic copying, various control systems areknown for controlling the processing steps to which a copy sheet issubjected in a copying apparatus, such as electrostatical charging,exposure, development and drying, such control systems incorporatingdevices of a purely electronic, an electromechanical and a purelymechanical nature. It applies to all such control systems as a commonrequirement that the individual processing steps should be performedautomatically in a prescribed sequence, so that the only manualoperation of the apparatus consists in pushing a start button and, ifnecessary, controlling the light intensity for the exposure by means,for example, of an adjustable light screen incorporated in the opticalsystem of the apparatus. Thus, the individual processing steps are oftencontrolled by micro switches, sensing members of which are arranged inthe conveying path for the copy sheet, so that the start and thetermination of each individual processing step is controlled directlythrough the advancement of the copy sheet. It is well known, however,that considerable adjustment problems often arise in connection withsuch micro switches, since the part of the sensing member to be actuatedby a paper sheet should be adjusted to a very accurate position in theconveying path. Furthermore the control of processing steps involvingthe movement of various mechanical components by means of such microswitches necessitates the use of solenoid actuated devices for imitatingthat movement.

A particular advantage of a copying apparatus of the above-mentionedkind is connected with the fact that before the reproduction process isstarted the original and the copy sheet are kept by their own weights inmutually spaced, substantially vertical start positions in which thelower edges of the original and the copy sheet are engaged by stopmembers inserted in their respective conveying paths, the rollers of afirst pair of advancing rollers in each conveying path being arrangedabove said stop members and being kept in a mutually spaced relation insaid start position. By simultaneously retracting the stop members froma conveying path and coupling together the said rollers in the sameconveying path, advancement of the original on the copy sheet,respectively, is started. This measure may be utilized to obtain acorrect alignment of the leading edges of the original and the copysheet at the beginning of the exposure step either by such aproportioning of the conveying paths for the original and the copysheet, respectively, that the distance between the step members and theupper edge of an exposure window is the same in both conveying paths orby employing a time delay from the retraction of the stop members fromthe copy sheet conveying path to the retraction of the stop members fromthe original conveying path. However, the retraction of such stopmembers from a conveying path and the coupling together of two rollersperformed simultaneously therewith represent a typical processing stepof the kind involving the movement of purely mechanical components whichwhen being imitated by sensor controlled micro switches can only bereleased by solenoid controlled actuating devices. In an apparatus ofthe kind set forth having the advantages of a low price and a compact,space-saving structure, the use of such actuating device will result inan undesiderable complication of the mechanical structure and anincrease of the manufacturing costs.

SUMMARY OF THE INVENTION It is an object of the invention to provide anelectrophotographic copying apparatus of the abovementioned compactstructure in which the individual processing steps are controlled bysimple and reliably operating programming means requiring only a minimumof space and securing an accurate synchronism between the advancementsof the original and the copy sheet, the only manual operation stillconsisting in pushing a start button and controlling the lightintensity, if necessary.

According to the invention there is provided an electrophotographiccopying apparatus, comprising mutually spaced, substantially verticalfirst and second conveying paths for an original to be reproduced and acopy sheet having a photosensitive surface to receive a reproduction ofsaid original, respectively;

a main driving system including an electric motor for advancing theoriginal and the copy sheet in a downwards direction along saidconveying paths;

an exposure lamp arranged at said first conveying path for illuminatingthe original;

a corona charging device, an exposure window, a developing device and adrying device arranged in order af succession in the advancing directionof the copy sheet along said second conveying path;

a supply of copy sheets arranged above said second conveying path;

a catch mechanism for taking off a single copy sheet at a time from saidsheet supply and advancing said sheet towards said second conveyingpath;

spring biased stop members arranged to be inserted into said first andsecond conveying paths for defining substantially vertical original anda copy sheet start positions at the upper ends of said conveying paths,the original and the copy sheet being kept in these start positions bytheir own weight;

and a pair of advancing rollers arranged in each of said conveying pathsabove said stop members, the rollers of each of said roller pairs beingremoved from each other when an original and a copy sheet are present insaid start positions,

i the spring biased stop members from each of said conwherein theimprovement comprises that programming means are provided, whichcomprise a first switching device for switching on and off the currentsupply to the electric motor of the main driving system; 5

a second switching device for switching on and off the current supply tothe corona charging device and the exposure lamp;

first and second control mechanisms for retracting 0 veyingpaths andsimultaneously coupling together the rollers of said rollers of saidroller pairs;

a number of actuating members for actuating and deactuating said firstand second switching devices and said first and second switching devicesand said first and second control mechanisms;

a manually operated start button to influence the actuating member forsaid first switching device;

a cam wheel connected with said catch mechanism;

and a single, circular disc-shaped timing member; mounted for rotationin the copying apparatus and cou-Y' pled with the main driving system,said timing member being provided on one lateral surface with a numberof radially displaced, substantially circular actuating surfacesections, each of which is in operative engagement with one of saidactuating members to operate said members in a timed sequence during asingle revolution of the timing member, the surface section associatedwith the actuating member for the first switching device being formed soas to operate said actuating memher to actuate the first switchingdevice to switch on the current supply to the electric motor of the maindriving system when said actuating member is influenced by said startbutton, whereby rotation of the timing member will be started, thetiming member furthermore having a number of teeth arranged in acircular are outside said actuating surface sections so as to get inoperative engagement with said cam wheel in a timed sequence with theoperation of said actuating members.

By these programming means all the individual steps of the reproductionprocess are controlled by said timing member. As soon as the timingmember has started its rotation which is initiated through operation ofthe start button, all the necessary actuations of the parts which are tobe mechanically moved during the individual steps are performed in thecourse ofa single revolution of the timing member by purely mechanicalactuation members without the use of solenoid controlled actuators. As aresult, a very reliable operation is obtained in which the need ofadjusting operations is reduced to a minimum.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 5 to 8 are sectional views alongthe lines V-V, VIVI, VIIVII and VIIIVIII, respectively, in FIG. 4; and.

FIGS. 9 to 13 illustrate various rotational phases of the timing membershown i FIGS. 4 to 8.

DETAILED DESCRIPTION In FIG. 1 an electrophotographic copying apparatusof the kind described in applicants above-mentioned US. patentapplication Ser. No. 358,325 is diagrammatically shown in a sectionalview along a vertical plane. In such an apparatus the original isscanned line by line during exposure under synchronous advancement ofthe original and the copy sheet by means of a stationary optical systemwhich forms an image of that part of the original which is momentarilypassing an exposure window in the original conveying path at an exposurestation disposed at the conveying path of the copy sheet.

Copy sheets are taken individually from a sheet supply l in theapparatus by means ofa turnable frictional catch mechanism 2 which onactuation performs a single complete revolution during part of which itcatches the nearest copy sheet in sheet supply 1, said copy sheet beingthereby advanced towards a start position for the advancement of thecopy sheet, the sheet being held vertically by its own weight in saidposition, the lower limit of which is defined by stop members 3 which inthe rest condition of the apparatus are inserted in the copy sheetconveying path immediately below the uppermost pair of advancing rollersin said path, the rollers 4 and 5 of said roller pair being kept in amutually spaced relation in said start position.

When reproduction has to take place stop members 3 are retracted fromthe copy sheet conveying path and simultaneously rollers 4 and 5 arecoupled together such as explained in the following. The copy sheet isthereafter in a manner known per se advanced through a corona chargingunit 6 in which the photosensitive surface of the sheet iselectrostatically charged, an exposure station 7 at which the sheetis'exposed to the image of an original, a development station 8 and adrying device 9 in order of succession, the copy sheet finally leavingthe apparatus through a discharge opening 10 at the bottom of theapparatus. The copy sheet advancement is performed by means of a rollerpair I l,

l2 between exposure station 7 and development station 8, a roller pairl3, 14 between development station 8 and drying device 9, said rollerpair also serving to sweep off excess developer liquid from the copysheet, anda roller pair 15, 16 arranged at discharge opening 10.

An original to be reproduced is inserted from above behind a cover 17which is pivotably mounted at the front of the apparatus in a manner notshown, until it assumes a start position for the advancement of theoriginal, in which the original is kept substantially ve rtically by itsown weight in the same way as the copy sheet in its start position, thelower limit of the original start position being defined by stop members18 which in the rest condition of the apparatus are inserted in theoriginal conveying path immediately below the uppermost pair ofadvancing rollers in said path, the rollers 19 and 20 of said pair beingkept in a mutually spaced relation in said start position. When the copysheet has started to move from its start position through the coronacharging unit 6 towards the exposure station 7,

stop members 18 are retracted from the original conveying path andsimultaneously rollers 19 and 20 are coupled together whereby theoriginal will beadvanced in synchronism with the advancement of the copysheet past an exposure window 21 through which it is imaged onto thecopy sheet by means of an optical system incorporating in a manner knownper se an exposure lamp 22, two inclined mirrors 23 and 24, a lenssystem 25 having a reflecting mirror 26 and a light screen member 27 foradjusting the light intensity. After having passed the exposure window21 the original is discharged from the apparatus below the cover 17 bymeans of a roller pair 28, 29.

FIG. 2 shows schematically the driving means for the advancement of theoriginal and the copy sheet in the apparatus shown in FIG. 1. The drivenrollers 4, 11, 14, 15 and 19, 28 in the conveying paths for the copysheet and the original, respectively, are rigidly connected withsprocket wheels which are designated by the same reference numerals astheir associated rollers, but provided with strokes. Roller 14 andsprocket wheel 14 are mounted on a shaft 30 which is connected with anelectric motor 31 through transmission means not shown, while sprocketwheels 4', ll, 14, 15, 19' 0g 28 are connected together by a chain 32and are proportioned in dependence on the diameters of their associatedrollers to that all of these rollers in operation of the apparatusrotate with equal peripheral velocities in the directions indicated byarrows.

To complete a reproduction process in the apparatus shown in FIG. 1 thefollowing individual operations have to be performed:

1. Starting the driving means shown in FIG. 2;

2. Advancing a single copy sheet from sheet supply 1 by means of catchmechanism 2 towards the start position;

3. Switching on corona charging unit 6 and exposure lamp 22;

4. Retracting stop members 3 from the copy sheet conveying path andcoupling together rollers 4 and 5. Retracting stop member 18 from theoriginal conveying path and coupling together rollers 19 and 20;

6. Switching off corona charging unit 6 and exposure lamps 22; and

7. Stopping the driving means shown in FIG. 2.

According to the invention, all these operations are controlled byprogramming means incorporating a single rotating timing member so thatthe only manual operation consists in pushing a start button shown at33. In the embodiment illustrated on the drawing said timing member isconstituted by a toothed timing wheel 34 meshing with a gear wheel 35which is rigidly connected with a sprocket wheel 36 meshing with chain32.

The function of timing wheel 34 and the actuating mechanism connectedtherewith will be explained in detail with reference to the perspectiveview shown in FIG. 3. The driving means shown in FIG. 2 are started andstopped and the corona charging unit 6 and the exposure lamp 22 areswitched on and off by means of micro switches 37, 38 and 39,respectively, having operation members and 41, operation member 41 beingcommon to contacts 38 and 39 which are incorporated in the currentsupply circuits for corona charging unit 6 an exposure lamp 22,respectively. Switches 37, 38 and 39 which are arranged at the oppositeside of the apparatus relative to the driving means shown in FIG. 2 areswitched by operation members 40 and 41 by axial displacement of switchactuating rods 42 and 43, respectively, which extend throughout thewidth of the apparatus and at right angles to timing wheel 34, saidswitch actuating rods being biased in the direction towards timing wheel34 such as indicated by arrows. The ends of switch actuating rods 42 and43 remote from switches 37 to 39 are situated in guide grooves 44 and45, respectively, which are formed in one lateral surface of timingwheel 34.

Stop members 3 in the copy sheet conveying path and stop members 18 inthe original conveying path are formed integrally with bars 46 and 47,respectively, engaging control rods 46 and 47 which are rigidlyconnected with actuating shafts 48 and 49, respectively, pivotablyjournalled in the apparatus, said actuating shafts being again rigidlyconnected with cam members 50 and 51, respectively, each of said cammembers being in engagement with a cam surface formed in timing wheel34. These cam surfaces are constituted by oppositely curved side walls52 and 53, respectively of a further guide groove 54 formed in timingwheel 34. The ends of bars 46 and 47 with their associated stop membersare restricted to movement in a horizontal plane such as shown for bar47, the ends of the bars being engaged by grooves such as shown at 47"which are formed in bearings secured to stationary walls of theapparatus.

Frictional catch mechanism 2 which serves to advance single copy sheetsfrom sheet supply 1 are mounted on a shaft 55 on one end of which a pinwheel 56 is secured said wheel being provided on one side with a memberof pins 57, in the embodiment shown six pins, to engage a correspondingnumber of teeth formed in the same lateral surface of timing wheel 34 asguide grooves 44, 45 and 54.

The detailed structure oftiming wheel 34 which may be moulded in onepiece from a plastic material will be apparent from the plane view shownin FIG. 4 and the sectional views shown in FIGS. Sto 8. The axialdisplacement of switch actuating rods 42 and 43 for actuating switchoperation members 40 and 41, respectively to change over micro switches37 and 38, 39 is accomplished in that each of the corresponding circularand concentric guide grooves 44 and 45 is divided into length portions,the bottom levels of which are displaced relative to each other, onebottom level corresponding to the actuated state and the other to thedeactuated state of the associated switch. Thus, guide groove 45associated with switch actuating rod 43 which serves for switching onand off corona charging unit 6 and exposure lamp 22 is divided into twolenght portions 59 and 60 having mutually displaced bottom levels. Asshown in FIGS. 6 and 8, the bottom face of the guide groove is inclinedat the bottom level displacement junctions 61 and 62 between the twolength portions 59 and 60, whereby switch actuating rod 43 when beingpassed by these junctions is subjected to the desired axial displacementfor changing over switches '38 and 39, said switches being actuated whenswitch actuating rod 43 is passed by junction 6] to switch on coronacharging unit 6 and exposure lamp 22 and being actuated to switch offsaid parts, when rod 43 is passed by junction 62. The portion ofjunctions 61 and 62 are chosen in dependance of the portion of switchactuating rod 43 relative to timing member 34 so that switching on andoff of switches 38 and 39 take place to the desired instants during areproduction process.

In a similar manner, guide groove 44 for switch actuating rod 42 servingto change over the micro switch 37 associated with the driving meansshown in FIG. 2 is divided into length portions 63 and 64 correspondingto the deactuated and actuated states, respectively, of switch 37.However, guide groove 44 is barried at the junction between lengthportions 63 and 64 on part of its width by a stop bar 65 which isengaged in the rest condition of the apparatus by the end of switchactuating rod 42 situated in guide groove 44. As shown in FIG. 1, thisend of switch actuating rod 42 is positioned in an operative relation tostart button 33, the switch actuating rod being supported in an inclinedslot in a partition wall in the apparatus so that switch actuating rod42 will be displaced in a radial direction of timing wheel 34, whenstart button 33 is depressed. Thereby, switch actuating rod 42 will bedisplaced from its position in length portion 63 in engagement with stopbar 65 to the part of the width of guide groove 44 which is not barredby stop bar 65, the bottom level of said part of the guide groove beingthe same as that of length portion 64, switch actuating rod 42 being,thereby, operated to actuate micro switch 37. As a result thereof, thedriving means illustrated in FIG. 2 are started and timing wheel 34begins its rotation. Since switch actuating rod 42 is biased asindicated by an arrow in FIG. 1

towards that part of the width of guide groove 44 which is barred bystop bar 65, it will subsequent to the passage of the. stop bar bereturned in a radial direction to said part of the guide groove.Normally, switch actuating rod 42 will be operated to deactuate microswitch 37 and stop the driving means illustrated in FIG. 2, when it ispassed by the inclined junction 67 between the above-mentioned lengthportions 64 and 63. However, guide groove 44 is formed so that it ispossible by depressing start button subsequent to the switching off ofthe corona charging unit and the exposure lamp to prevent the drivingmeans from being stopped, the part of the width of guide groove 44 whichis not barred by stop bar 65 having along a corresponding length portion68, a third bottom level which is different from the bottom levels oflength portions 63 and 64, but which corresponds to the actuated stateof micro switch 37 just like the bottom level oflength portion 64. Thus,by a radial displacement resulting from depression of start button 33,which actuating rod 42 will be moved into 4 length portion 68 in steadof assuming the bottom level of length portion 63 by being passed byinclined junction 67. Thereafter, the end of switch actuating rod 42will again be displaced axially to assume the bottom level of lengthportion 64 by being passed by junction 69 between length portions 68 and64.

The opposite side walls of guide groove 54 in timing wheel 34 whichserve as cam faces for cam members 50 and 51 to retract stop members 3and 18 away from the conveying paths for the copy sheet and theoriginal, respectively, are formed with abrupt surface discontinuitiesas shown at 70 and 71, by the passage of which cam members 50 and 51will be subjected to such a radial displacement relative to timing wheel34 that stop members 3 and 18 as a result of the turning of actuatingshafts 48 and 49, respectively, caused thereby will be pivoted out ofthe conveying paths of the copy sheet and the original respectively.

The various rotational phases of timing wheel 34 are illustrated inFIGS. 9 to 13 which also show the positions of switch actuating rods 42and 43 and the parts of cam members 50 and 51 which are in engagementwith cam faces 52 and 53, respectively, of timing wheel 34. In FIG. 9the start position for the rotation of timing wheel 34 is shown, inwhich position switch actuating rod 42 engages stop bar 65. The drivingmeans are actuated by a radial displacement of the switch actuating rodto the position shown by a dotted circle, when the start button 33 isoperated, whereby timing wheel 34 begins its rotation. In the positionshown in FIG. 10, in which timing wheel 34 has rotated about 35 from thestart position, teeth 58 on timing wheel 34 has rotated pin wheel 56 incatch mechanism 2 by such an amount that a single copy sheet from sheetsupply 1 has been advanced to the copy sheet start position.Furthermore, in this position switch actuating rod 43 is passed byjunction 61 in guide groove 45, whereby corona charging unit 6 andexposure lamp 22 are switched on, while cam member 50 is passed bydiscontinuity of cam face 52, whereby stop member 3 are retracted fromthe copy sheet conveying path and advancing rollers 4 and 5 are coupledtogether. In the position shown in FIG. 11, in which timing wheel 34 inthe embodiment shown has rotated 45,3 from the start position, cammember 51 is passed by discontinuity 71 of cam face 53, whereby stopmembers 18 are retracted from the original conveying path and advancingrollers 19 and 20 are coupled together. The relative angular positionsof discontinuities 70 and 71 is chosen in dependence on the relativepositions of cam members 50 and 51 so that the time delay between thepositions shown in FIGS. 10 and 11 corresponds to the difference betweenthe distance from stop members 3 to the upper edge of the window in theexposure station associated with the copy sheet conveying path and thedistance between stop member 18 and the upper edge of exposure window 21in the original conveying path. In the position shown in FIG. 12, inwhich timing wheel 34 in the embodiment shown has rotated about 235 fromthe start position, switch actuating rod 43 is passed by junction 62 inguide groove 45, whereby corona charging unit 6 and exposure lamp 22 areswitched off. In the position shown in FIG. 13, in which timing wheel 34has rotated about 325 from the start position switch actuating rod 42will be passed byjunction 67 in guide groove 44, provided it has notalready been radially displaced by operation of start button 33, wherebymicro switch 37 will be deactuated to stop the driving means, so thattiming wheel reassumes the position shown in FIG. 9. If start button 33has been operated before the timing wheel reaches the position shown inFIG. 13, the deactuation of switch actuating rod 42 will be prevented inthe manner already explained.

As already mentioned it is necessary in order to obtain an accuratepositioning of the original and the copy sheet in their respective startpositions in the copying apparatus according to the invention thatrollers 4 and 5 in the first pair of advancing rollers in the copy sheetconveying path as well as rollers 19 and 20 in the first pair ofadvancing rollers in the original conveying path are kept in a mutuallyspaced relation in the rest condition of the apparatus. According to theinvention this is obtained in that the non-driven roller in each of saidroller pairs, i.e., rollers and 20, is resiliently supported and isbiased towards engagement with the driven roller in the same rollerpair, i.e. rollers 4 and 19, respectively, the support for saidnon-driven roller and the stop member associated with the conveying pathin question being formed so that the stop member in the postion in whichit is inserted in the conveying path exerts a force on said rollersupport in a direction opposite to that of the applied bias, whereby thenon-driven roller is displaced away from the position, in which itengages the driven roller. As soon as the stop member is actuated fromtiming wheel 34 to be retracted from the conveying path in question, thenondriven roller 5 or will be brought into engagement with the drivenroller 4 or 19. Thus, in the embodiment shown in FIG. 1 of the copyingapparatus according to the invention the non-driven rollers 20 and 29 inthe original conveying path are mounted on a support member 72 which isresiliently suspended relative to cover 17, so that rollers 20 and 29are biased towards engagement with rollers 19 and 28, respectively. Justbelow roller 20 support member 72 has a protusion 73 facing the originalconveying path for being engaged by stop member 18 in the position, inwhich the stop member is inserted in the conveying path. In a similarmanner, non-driven rollers 5 and 12 in roller pairs 4, 5 and 11, 12 inthe copy sheet conveying path are mounted on a support member 74 whichis resiliently supported relative to a back wall 75 of the apparatussuch as shown schematically in FIG. 1 and is biased towards theposition, in which both rollers 5 and 12 engage rollers 4 and 11,respectively. Support member 74 has a form so that part of saidmemberjust below roller 5 forms an abutment for stop member 3 in theposition, in which the stop member is inserted in the copy sheetconveying path. As shown in FIG. 1, support member 74 may also carry thebackward half part of corona charging unit 6, so that direct access tothe portion of the copy sheet conveying path extending between rollerpairs 4, 5 and ll, 12 may be obtained by opening the apparatus at theback wall.

What is claimed is:

1. An electrophotographic copying apparatus, comprising mutually spaced,substantially vertical first and second conveying paths for an originalto be reproduced and a copy sheet having a photosensitive surface toreceive a reproduction of said original, respectively;

a main driving system including an electric motor for advancing theoriginal and the copy sheet in a downwards direction along saidconveying paths;

an exposure lamp arranged at said first conveying path for illuminatingthe original;

a corona charging device, an exposure window, a developing device and adrying device arranged in order of succession in the advancing directionof the copy sheet along said second conveying path;

a supply of copy sheets arranged above said second conveying path;

a catch mechanism for taking off a single copy sheet at a time from saidsheet supply and advancing said sheet towards said second conveyingpath;

spring biased stop members arranged to be inserted into said first andsecond conveying paths for defining substantially vertical original andcopy sheet start positions at the upper ends of said conveying paths,the original and the copy sheet being kept in these start positions bytheir own weight;

and a pair of advancing rollers arranged in each of said conveying pathsabove said stop members, the rollers of each of said roller pairs beingremoved from each other when an original and a copy sheet are present insaid start positions,

wherein the improvement comprises that programming means are provided,which comprise a first switching device for switching on and off thecurrent supply to the electric motor of the main driving system;

a second switching device for switching on and off the current supply tothe corona charging device and the exposure lamp;

first and second control mechanisms for retracting the spring biasedstop members from each of said conveying paths and simultaneouslycoupling together the rollers of said roller pairs;

a number of actuating members for actuating and deactuating said'firstand second switching devices and said first and second controlmechanisms;

at mannually operated start button to influence the actuating member forsaid first switching device;

a cam wheel connected with said catch mechanism;

and' a single, circular disc-shaped timing member mounted for rotationin the copying apparatus and coupled with the main driving system, saidtiming member being provided on one lateral surface with a number ofradially displaced, substantially circular actuating surface sections,each of which is in operative engagement with one of said actuatingmembers to operate said members in a timed sequence during a singlerevolution of the timing member, the surface section associated with theactuating member for the first switching device being formed so as tooperate said actuating member to actuate the first switching device toswitch on the current supply to the electric motor of the main drivingsystem when said actuating member is influenced by said start button,whereby rotation of the timing member will be started, the timing memberfurthermore having a number of teeth arranged in a circular arc outsidesaid actuating surface sections so as to get in operative engagementwith said cam wheel in a timed sequence with the operation of saidactuating members.

2. An electrophotographic copying apparatus as claimed in claim 1,wherein the actuating member for the first switching device is formed soas to prevent deactuation of said switching device when the start buttonis reoperated before the termination of said single revolution of thetiming member.

3. An electrophotographic copying apparatus as claimed in claim 1,wherein the actuating members for the first and second switching devicesare constituted by axially displaceable switch actuating rods extendingat right angles to said one lateral surface of the timing member andbeing biased in the axial direction towards the timing member, theassociated actuating surface sections on the timing member beingconstituted by bottom faces of substantially circular guide grooves forsaid switch actuating rods, each of said bottom faces being subject to alevel displacement between the parts of the length of the guide groovecorresponding to the actuated and deactuated state for the associatedswitching device, respectively.

4. An electrophotographic copying apparatus as claimed in claim 3,wherein the guide groove for the switch actuating rod associated withsaid first switching device is barred in a given position on part of itswidth by a stop bar, one side of which serves to engage the switchactuating rod in the rest condition of the apparatus, the bottom face ofsaid part of the guide groove lying in said given position at a firstlevel corresponding to the deactuated state of the first switchingdevice, the end of the switch actuating rod situated in the guide groovebeing adapted to be engaged by said start but- .ton at operation of thestart button so as to be radially displaceable relative to the timingmember to the part of the width of the guide groove which is not barredby said stop bar, the bottom face of the lastmentioned part of the guidegroove assuming, in said given position, together with the bottom faceof the guide groove on the other side of the stop bar a second levelcorresponding to the actuated state of the first switching device, theswitch actuating rod being biased in the radial direction of the timingmember towards the part of the width of the guide groove which is barredby the stop bar.

5. An electrophotographic copying apparatus as claimed in claim 4,wherein the bottom face of said part of the width of said guide groovewhich is not barred by said stop bars lies through a portion at itslength which during rotation of the timing member passes said switchactuating rod subsequent to deactuation of said second switching deviceat a third level which is different from said first and second bottomface levels, but corresponds to the actuated state of said firstswitching device, whereby the switch actuating rod by being radiallydisplaced as a result of operation of the start button will be preventedform assuming said first bottom face level.

6. An electrophotographic copying machine as claimed in claim 1, whereinthe control mechanisms for retracting said stop members from said firstand second conveying paths comprise shafts which are pivotablyjournalled in the apparatus and each of which is rigidly connected, onone hand, with the stop members associated with one of said conveyingpaths and, on the other hand, with the actuating member associated withsaid stop members, each of said lastmentioned actuating members beingconstituted by a cam member and the corresponding actuating surfacesection on the timing member being constituted by. a cam surface, saidcam surface forming opposite, curved lateral surfaces of a furthersustantially circular guide groove, in each of which lateral surfacessuch a discontinuity is provided in a position at which actuation'of thecorresponding cam member has to take place that said cam member whenbeing passed by said discontinuity will actuate the corresponding shaftto pivot the stop members away from the associated conveying path.

7. An electrophotographic copying machine as claimed in claim 6, whereineach of the roller pairs arranged above the stop members associated withsaid first and second conveying paths, respectively, comprises anon-driven roller, a resilient support for said roller and a drivenroller coupled with said main driving system, said support being biasedtowards engagement of the non-driven roller with the driven roller, thestop members for the associated conveying path being formed so as toexert in the positionin which they are inserted in the conveying path, aforce on said support against the direction of the bias, whereby thenondriven roller will be kept in a position spaced from the drivenroller and may be brought into engagement with said roller by retractingthe stop members from the conveying path.

1. An electrophotographic copying apparatus, comprising mutually spaced,substantially vertical first and second conveying paths for an originalto be reproduced and a copy sheet having a photosensitive surface toreceive a reproduction of said original, respectively; a main drivingsystem including an electric motor for advancing the original and thecopy sheet in a downwards direction along said conveying paths; anexposure lamp arranged at said first conveying path for illuminating theoriginal; a corona charging device, an exposure window, a developingdevice and a drying device arranged in order of succession in theadvancing direction of the copy sheet along said second conveying path;a supply of copy sheets arranged above said second conveying path; acatch mechanism for taking off a single copy sheet at a time from saidsheet supply and advancing said sheet towards said second conveyingpath; spring biased stop members arranged to be inserted into said firstand second conveying paths for defining substantially vertical originaland copy sheet start positions at the upper ends of said conveyingpaths, the original and the copy sheet being kept in these startpositions by their own weight; and a pair of advancing rollers arrangedin each of said conveying paths above said stop members, the rollers ofeach of said roller pairs Being removed from each other when an originaland a copy sheet are present in said start positions, wherein theimprovement comprises that programming means are provided, whichcomprise a first switching device for switching on and off the currentsupply to the electric motor of the main driving system; a secondswitching device for switching on and off the current supply to thecorona charging device and the exposure lamp; first and second controlmechanisms for retracting the spring biased stop members from each ofsaid conveying paths and simultaneously coupling together the rollers ofsaid roller pairs; a number of actuating members for actuating anddeactuating said first and second switching devices and said first andsecond control mechanisms; a mannually operated start button toinfluence the actuating member for said first switching device; a camwheel connected with said catch mechanism; and a single, circulardisc-shaped timing member mounted for rotation in the copying apparatusand coupled with the main driving system, said timing member beingprovided on one lateral surface with a number of radially displaced,substantially circular actuating surface sections, each of which is inoperative engagement with one of said actuating members to operate saidmembers in a timed sequence during a single revolution of the timingmember, the surface section associated with the actuating member for thefirst switching device being formed so as to operate said actuatingmember to actuate the first switching device to switch on the currentsupply to the electric motor of the main driving system when saidactuating member is influenced by said start button, whereby rotation ofthe timing member will be started, the timing member furthermore havinga number of teeth arranged in a circular arc outside said actuatingsurface sections so as to get in operative engagement with said camwheel in a timed sequence with the operation of said actuating members.2. An electrophotographic copying apparatus as claimed in claim 1,wherein the actuating member for the first switching device is formed soas to prevent deactuation of said switching device when the start buttonis reoperated before the termination of said single revolution of thetiming member.
 3. An electrophotographic copying apparatus as claimed inclaim 1, wherein the actuating members for the first and secondswitching devices are constituted by axially displaceable switchactuating rods extending at right angles to said one lateral surface ofthe timing member and being biased in the axial direction towards thetiming member, the associated actuating surface sections on the timingmember being constituted by bottom faces of substantially circular guidegrooves for said switch actuating rods, each of said bottom faces beingsubject to a level displacement between the parts of the length of theguide groove corresponding to the actuated and deactuated state for theassociated switching device, respectively.
 4. An electrophotographiccopying apparatus as claimed in claim 3, wherein the guide groove forthe switch actuating rod associated with said first switching device isbarred in a given position on part of its width by a stop bar, one sideof which serves to engage the switch actuating rod in the rest conditionof the apparatus, the bottom face of said part of the guide groove lyingin said given position at a first level corresponding to the deactuatedstate of the first switching device, the end of the switch actuating rodsituated in the guide groove being adapted to be engaged by said startbutton at operation of the start button so as to be radiallydisplaceable relative to the timing member to the part of the width ofthe guide groove which is not barred by said stop bar, the bottom faceof the lastmentioned part of the guide groove assuming, in said givenposition, together with the bottom face of the guide groove on the otherside of the stop bar a second level corresponDing to the actuated stateof the first switching device, the switch actuating rod being biased inthe radial direction of the timing member towards the part of the widthof the guide groove which is barred by the stop bar.
 5. Anelectrophotographic copying apparatus as claimed in claim 4, wherein thebottom face of said part of the width of said guide groove which is notbarred by said stop bars lies through a portion at its length whichduring rotation of the timing member passes said switch actuating rodsubsequent to deactuation of said second switching device at a thirdlevel which is different from said first and second bottom face levels,but corresponds to the actuated state of said first switching device,whereby the switch actuating rod by being radially displaced as a resultof operation of the start button will be prevented form assuming saidfirst bottom face level.
 6. An electrophotographic copying machine asclaimed in claim 1, wherein the control mechanisms for retracting saidstop members from said first and second conveying paths comprise shaftswhich are pivotably journalled in the apparatus and each of which isrigidly connected, on one hand, with the stop members associated withone of said conveying paths and, on the other hand, with the actuatingmember associated with said stop members, each of said lastmentionedactuating members being constituted by a cam member and thecorresponding actuating surface section on the timing member beingconstituted by a cam surface, said cam surface forming opposite, curvedlateral surfaces of a further sustantially circular guide groove, ineach of which lateral surfaces such a discontinuity is provided in aposition at which actuation of the corresponding cam member has to takeplace that said cam member when being passed by said discontinuity willactuate the corresponding shaft to pivot the stop members away from theassociated conveying path.
 7. An electrophotographic copying machine asclaimed in claim 6, wherein each of the roller pairs arranged above thestop members associated with said first and second conveying paths,respectively, comprises a non-driven roller, a resilient support forsaid roller and a driven roller coupled with said main driving system,said support being biased towards engagement of the non-driven rollerwith the driven roller, the stop members for the associated conveyingpath being formed so as to exert in the position in which they areinserted in the conveying path, a force on said support against thedirection of the bias, whereby the non-driven roller will be kept in aposition spaced from the driven roller and may be brought intoengagement with said roller by retracting the stop members from theconveying path.